Today, I will show you how to create customized USB flash drive to boot selected ISO images using Syslinux bootloader for Linux ext4 filesystem. It is very handy and useful, so let’s begin immediately.
Requirements
Install syslinux bootloader for ext4 filesystem to use modern Linux filesystem..
$ sudo apt-get install extlinux
syslinux-common package will be installed as dependency – it is very important as it contains many required files.Step 1
Create one big partition on USB drive and make it active.
/dev/sdc as an USB drive in this example.$ sudo sfdisk /dev/sdc << EOF ,+,L,* EOF
sfdisk: Checking that no-one is using this disk right now ... sfdisk: OK Disk /dev/sdc: 14800 cylinders, 64 heads, 32 sectors/track Old situation: Units: cylinders of 1048576 bytes, blocks of 1024 bytes, counting from 0 Device Boot Start End #cyls #blocks Id System /dev/sdc1 0 - 0 0 0 Empty /dev/sdc2 0 - 0 0 0 Empty /dev/sdc3 0 - 0 0 0 Empty /dev/sdc4 0 - 0 0 0 Empty New situation: Units: cylinders of 1048576 bytes, blocks of 1024 bytes, counting from 0 Device Boot Start End #cyls #blocks Id System /dev/sdc1 * 0+ 14799 14800- 15155199+ 83 Linux /dev/sdc2 0 - 0 0 0 Empty /dev/sdc3 0 - 0 0 0 Empty /dev/sdc4 0 - 0 0 0 Empty Successfully wrote the new partition table Re-reading the partition table ... sfdisk: If you created or changed a DOS partition, /dev/foo7, say, then use dd(1) to zero the first 512 bytes: dd if=/dev/zero of=/dev/foo7 bs=512 count=1 (See fdisk(8).)
Read sfdisk partition table manipulator for Linux manual page for more detailed information.
$ man sfdisk
Step 2
Format it as ext4 without journal to get the benefits of modern filesystem.
$ sudo mkfs.ext4 -F -O ^has_journal /dev/sdc1 mke2fs 1.42.12 (29-Aug-2014) /dev/sdc1 contains a ext4 file system created on Sun Sep 27 21:40:45 2015 Creating filesystem with 3788799 4k blocks and 948416 inodes Filesystem UUID: 655f27e9-dee2-4ac3-9014-76fa711432e1 Superblock backups stored on blocks: 32768, 98304, 163840, 229376, 294912, 819200, 884736, 1605632, 2654208 Allocating group tables: done Writing inode tables: done Writing superblocks and filesystem accounting information: done
Step 3
Install Master Boot Record (included in mentioned earlier syslinux-common package).
$ sudo dd bs=440 count=1 conv=notrunc if=/usr/lib/syslinux/mbr/mbr.bin of=/dev/sdc
1+0 records in 1+0 records out 440 bytes (440 B) copied, 0,00827953 s, 53,1 kB/s
Read MBR (Master Boot Record) – Syslinux Wiki document for detailed information.
Step 4
Create temporary directory to mount partition created in the first step.
$ sudo mkdir -p /media/usb
Mount created partition.
$ sudo mount /dev/sdc1 /media/usb/
Step 5
Create boot/extlinux boot directory.
$ sudo mkdir -p /media/usb/boot/extlinux
Install syslinux bootloader on ext4 filesystem.
$ sudo extlinux --install /media/usb/boot/extlinux/ /media/usb/boot/extlinux/ is device /dev/sdc1
Step 6
Copy memdisk module to the boot directory.
$ sudo cp /usr/lib/syslinux/memdisk /media/usb/boot/extlinux/
memdisk is a module which simulates a disk to allow booting legacy operating systems.
Step 7
Copy modules required to display menu, boot from hard drive and reboot system.
$ sudo cp /usr/lib/syslinux/modules/bios/{menu.c32,reboot.c32,chain.c32,libutil.c32,libcom32.c32} /media/usb/boot/extlinux/
Module dependencies are described at Syslinux modules working dependencies wiki page.
Step 8
Create basic boot menu and store it in /media/usb/boot/extlinux/extlinux.conf file.
DEFAULT menu.c32
PROMPT 0
MENU TITLE Bootable USB drive
MENU BEGIN Boot from hard drive
MENU TITLE Boot from hard drive
LABEL boot_hd0
MENU LABEL Boot from ^first hard drive
MENU INDENT 1
COM32 chain.c32
APPEND hd0
TEXT HELP
* Boot from first hard drive
ENDTEXT
LABEL boot_hd1
MENU LABEL Boot from ^second hard drive
MENU INDENT 1
COM32 chain.c32
APPEND hd1
TEXT HELP
* Boot from second hard drive
ENDTEXT
MENU END
LABEL reboot
MENU LABEL ^Reboot
MENU INDENT 1
COM32 reboot.c32
TEXT HELP
* Reboot system
ENDTEXT
Step 9
Create images directory.
$ sudo mkdir -p /media/usb/images
Store ISO images inside this directory.
Step 10
Configure syslinux bootloader to boot ISO images.
I will show you three examples that will allow you to test and use most of the available ISO images. I know about one notable exception, but it will be described next time.
Super Grub2 Disk
This is the simplest task as it does not require anything more then memdisk module.
Step A
Download super_grub2_disk_hybrid_2.02s3.iso ISO image from supergrubdisk.org and store it inside /media/usb/images/ directory.
Step B
Create boot menu entry.
LABEL super_grub MENU LABEL Emergency Linux boot LINUX memdisk INITRD /images/super_grub2_disk_hybrid_2.02s3.iso APPEND iso TEXT HELP * Boot into Linux system with broken GRUB2 bootloader ENDTEXT
Clonezilla
This process is very similar to the previous one.
Step A
Download clonezilla-live-2.4.2-32-amd64.is ISO image from clonezilla.org and store it inside /media/usb/images/ directory.
Step B
Create boot menu entry.
LABEL clonezilla MENU LABEL Clonet i LINUX memdisk INITRD /images/clonezilla-live-2.4.2-32-amd64.iso APPEND iso TEXT HELP * Clonezilla live version: 2.4.2-32-amd64. (C) 2003-2015, NCHC, Taiwan ENDTEXT
Ubuntu Desktop Live
memdisk does not work in more complicated setups, including often used casper hook for initramfs-tools to boot live systems. However, the solution is to extract kernel and initrd from ISO file, then use them to boot the image.
Step A
Download ubuntu-15.04-desktop-amd64.iso ISO image from ubuntu.com and store it inside /media/usb/images/ directory.
Step B
Extract kernel (vmlinuz.efi) and initrd image (initrd.lz) from casper directory inside ISO image and store them on USB flash drive (inside boot/ubuntu/ directory).
Step C
Create boot menu entry.
LABEL ubuntu_live MENU LABEL Live non-persistent desktop LINUX /boot/ubuntu/vmlinuz.efi APPEND boot=casper initrd=/boot/ubuntu/initrd.lz iso-scan/filename=/images/ubuntu-15.04-desktop-amd64.iso TEXT HELP * Ubuntu 15.04 desktop 64-bit ENDTEXT
Simple as that.
Additional notes
I could not boot Tails 1.6, but maybe it is related to this specific version.
Debian Jessie requires some additional work, so I decided to publish these instructions separately. You can expect them next week.